net: rtnetlink: add bulk delete support flag

Add a new rtnl flag (RTNL_FLAG_BULK_DEL_SUPPORTED) which is used to
verify that the delete operation allows bulk object deletion. Also emit
a warning if anyone tries to set it for non-delete kind.

Suggested-by: David Ahern <dsahern@kernel.org>
Signed-off-by: Nikolay Aleksandrov <razor@blackwall.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/net/rtnetlink.h b/include/net/rtnetlink.h
index 0bf6224..bf8bb33 100644 (file)
--- a/include/net/rtnetlink.h
+++ b/include/net/rtnetlink.h
@@ -10,7 +10,8 @@ typedef int (*rtnl_doit_func)(struct sk_buff *, struct nlmsghdr *,
 typedef int (*rtnl_dumpit_func)(struct sk_buff *, struct netlink_callback *);
 
 enum rtnl_link_flags {
-       RTNL_FLAG_DOIT_UNLOCKED = BIT(0),
+       RTNL_FLAG_DOIT_UNLOCKED         = BIT(0),
+       RTNL_FLAG_BULK_DEL_SUPPORTED    = BIT(1),
 };
 
 enum rtnl_kinds {

diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
index beda4a7..63c7df5 100644 (file)
--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c
@@ -249,6 +249,8 @@ static int rtnl_register_internal(struct module *owner,
        if (dumpit)
                link->dumpit = dumpit;
 
+       WARN_ON(rtnl_msgtype_kind(msgtype) != RTNL_KIND_DEL &&
+               (flags & RTNL_FLAG_BULK_DEL_SUPPORTED));
        link->flags |= flags;
 
        /* publish protocol:msgtype */
@@ -6009,6 +6011,12 @@ static int rtnetlink_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh,
        }
 
        flags = link->flags;
+       if (kind == RTNL_KIND_DEL && (nlh->nlmsg_flags & NLM_F_BULK) &&
+           !(flags & RTNL_FLAG_BULK_DEL_SUPPORTED)) {
+               NL_SET_ERR_MSG(extack, "Bulk delete is not supported");
+               goto err_unlock;
+       }
+
        if (flags & RTNL_FLAG_DOIT_UNLOCKED) {
                doit = link->doit;
                rcu_read_unlock();